Manufacture of nitrogenic and phosphatic combinations



I ited, particularly when a complete fertilizer Patented Oct. 27, 1925.

UNITED STATES PATENT OFFICE.

JOSEPH BRESLAU'ER, or GEREVA, SWITZERLAND; AND GEORGES DARIER, or BORDLGHERA, ITALY, ASSIGNORS .ro socn'z'rs DETUDES CHIMIQUES POUR LINDUSTRIE,

or GENEVA, SWITZERLAND, A CORPORATION or SWITZERLAND.

MANUFACTURE OF NITRQGENIC AND PHOSPHATIC COMBINATIONS.

No Drawing. Original application filed September 18, 1920, Serial No.411,074. Divided and this application filed May 29, 1925. Serial No.33,836.

I '0 all whom it mag 100mm:

Be it known that we, JOSEPH BRESLAUER, a citizen of Switzerland,residing at Geneva, Switzerland, and GEORGES DARIER, a citizen ofSwitzerland, residing at Bordighera, in Italy, have invented certain newand useful Improvements in Manufacture of Nitrogenic and PhosphaticCombinations, of which the following is a'specification.

Our resent invention relates to a process of pro ucing fertilizers and,more particularly, to a process of transforming crude calcium cyanamidto substances which may be mixed with other fertilizing materia such asphosphates, in forming a complete fertilizer.

The present invention is a division of our co-pending application SerialNo. 411,074, filed Sept. 18th, 1920.

Calcium cyanamid or raw cyanamid contains a quantity of free lime or ofcalcium weakly combined with the cyanamid which, if mixed with a solubleacid phosphate, would render the phosphate insoluble by combination withthe calcium content of the raw. cyanamid, and thereby render itvalueless- The application of the raw cyanamid for fertilizing purposesis accordingly limis desired. -This difficult-y has been overcome in theprocess described in the above application, from which the presentapplica tion has been divided, by transforming the raw cyanamid intofree cyanamid and thence description, the invention comprises theprocess described in the following specification and claims.

In our present invention, a mixed phosphatic and nitrogenic fertilizeris produced by introducing raw cyanamid in successive phosphate solutionor phosphoric acid into which the raw cyanamid is mixed may coninto ureaor acid solutions of urea which.

may be mixed directly with phosphates or other fertilizing materials. IThe present invention relates to modifications and improvements on theprocess of the above identified application and has among its objects tosimplify and cheapen the process of forming a complete fertilizer and toprovide a process bywhich the compound or mixerl fertilizer may beformed in a simpler and more direct manner and in which a wide'range ofproportions of phosphatic and nitrogenic materials may be obtained. 7

With these and other objects in View, which will be apparent from thefollowing tain some free cyanamid formed previously by precipitating themetallic constituents of raw cyanamid in an acid medium, such forexample as a solution of carbonic acid. The acid phosphate. solution mayconsist of a solution of an acid phosphate or of pure phosphoric acid orphosphoric acid containing sulphuric acid present in the crude acidobtained by the action of sulphuric acid on phosphates.

phosphoric acid containing. a :quantity )of free cyanamid, the freecyanamid may be formed by adding raw cyanamid in small portions to waterto which carbon dioxide is applied in quantity sufficient to precipitatethe metallic constituents of the raw cyanamid and to form a slightlyacid solution, the water being actively stirred or agitated to keep theraw cyanamid suspended in finely divided condition sothat it remains inintimate contact with the dissolved car- When it is desired to form asolution I.

.bon dioxide and to bring the carbonic acid solution into uniformcontact with the suspended raw cyanamid. During .the addi- -tion of theraw 0 anamid, the water. is kept cool and the addition of raw cyanamidand carbondioxide are so regulated as to precipitate the metallicconstituents as rapidly as the; are added and to bring the so1u Y tionto. substantial acidity The precipitated insoluble salts are thenremoved from the solution by filtration or other suitable riched in freecyanamid by further repeated additions of raw cyanamid and carbondioxide and subsequent filtrations.

A solution of free cyanamid prepared as further quantity of finelydivided raw cyanamid maybe added to the resulting acid solution, theacid of the solution reacting with the calcium of ;the raw cyanamid toform a soluble acid phosphate. The uantities of free cyanamid,phosphoric aci and raw cyanamid may be varied to obtain any required.proportionsof nitrogen and phosphorus, provided the quantity of rawcyanamid is not so great as to form insoluble tricalcium phosphate. Themixture may then be heated to a temperature suflicient to transform thefree cyanamid to urea, a temperature of from 60 C. to C. being'suitablefor this purpose. 0

As an example, to an aqueous solution containing 44 kilograms of freecyanamld, and 98 kilograms of phosphoric acid there is added, little bylittle and with constant stirring, kilograms of commercial calciumcyanamid.

The mass heats gradually and, when all of the calcium cyanamid has beenadded, it takes the form of more or less solid, moist, granules, whichit is only necessary to dry 'and put into sacks for use. The massrepresents a nitro-phosphate fertilizer containing about 20 per cent ofass'imilable nitrogen and 40 per cent of phosphoric acid soluble inwater and in citrates in the form of monoand bi-calcium phosphates.

The phosphoric acid in the above example may contain sulphuric acid,which servesto it is desired that all comprises, forming a solution offree cyanamid; and converging said free cyanamid in solution into unreaby means of an acid salt.

2. A process of the type described which comprises, forming a solutionof free cyanamid and converging said freecyanamid in solution. into ureaby means of an acid salt of phosphoric acid.

3. A process of the type described which comprises, forming a solutionof free cyanresultin acid solution of free cyanamid-to urea an adding tothe resulting acid solution a calcium phosphate to form a soluble amidin small portions to a solution maintamed acid with an acid salt,hydrating the nitro-phosphate fertilizer without isolating itsconstituents.

5. ,A process of the type described which comprises, adding finelydivided raw cyanamid in small portions to a solution maintained acidwith an acid salt and hydrating the resulting acid solution of freecyan-' amid to urea.

6. A process of the type described which comprises, forming a solutionof free cyanamid and an acid agent containing a phos phate radical,adding raw calcium cyanamid to said solution little by little, andpermitting the resulting mixture t-oheat up to transform the freecyanamid to urea, the concentration of said solution andthe quantity ofraw calcium cyanamid added being sufiicient to form a soluble phosphateand to form moist solid granules are combined nitrogenic and phos haticfertilizer.

'7. A process of t e type described which comprises, adding finelydivided raw cyanamid in small portions to asolution maintained acid withan acid salt of phos horic acid, hydrating the resulting acid soution offree cyanamid to urea and addin the resultm acid solution a calcium sa tto form with the acid mixture 8. nitrophosphate fertilizer withoutisolating its constituents.

In'testimony whereof, we afiix our signatures.

JOSEPH BRESLAUER. GEORGES DARIER.

